Current cars, trucks and other vehicles or devices driven by gasoline-fueled internal combustion engines include an on-board computer to provide means for electronically controlling the various systems and devices incorporated in these vehicles.
As is well known in the art, and as explained in copending U.S. patent application Ser. No. 07,662,568 and the above Ser. No. 07/726,788, the basic components of a typical prior art electronically-controlled gasoline fuel injection system in such vehicles are generally as follows:
1. a fuel tank;
2. an electric fuel pump;
3. a pressure regulator for maintaining the pressure of the fuel supplied by the fuel pump at a required constant pressure;
4. sensors appropriately mounted on the engine or vehicle, each producing an electrical signal representative of the instantaneous value of one of the various conditions under which the engine must operate, and in accordance with which the quantity of fuel supplied to the engine is to be controlled;
5. a solenoid-operated or other suitable electronically-controlled fuel injector(s) for supplying a metered quantity of the pressure-regulated fuel to the engine induction system or directly to the individual engine cylinders;
6. an electronic control unit (ECU), which may be part of the on-board computer, for receiving, as inputs thereto, the electric signals generated by the sensors and producing, as the output therefrom, an integrated electrical signal controlling the injector(s);
7. a direct current electrical power source, such as a battery and/or an alternator;
8. appropriate electrical switches and conductors connecting the electrical/electronic components (electrical circuit) of the system; and
9. appropriate fuel conduits connecting the fuel components (hydraulic circuit) of the system. Examples of such a typical prior art systems are taught, as explained in U.S. Ser. No. 07,662,568, by the following U.S. Pat. Nos.:
______________________________________ 4,292,945 4,590,911 4,878,418 3,604,401 4,532,893 4,109,669 4,265,200 2,108,115 ______________________________________
Persons skilled in the internal combustions engine art understand the following principles relating thereto:
a) at any given speed (RPM), the engine may be developing minimum, intermediate or maximum power; PA1 b) engine fuel consumption varies, and, at any given speed, fuel consumption depends upon the power taken out of the engine; PA1 c) speed and power requirements determine fuel consumption and PA1 d) even at engine idle speed which usually involves low fuel consumption, more vehicle accessories in operation requires more power, and thus increased fuel consumption. PA1 (a) For one thing, substantial energy (gasoline to provide the power required to operate the pump) is being wasted pumping fuel to approximately 30-40 psi, and consuming very little (about 20%) of the total pumped fuel. PA1 (b) More importantly, vapor is being churned out of the fuel, which is undesirable and must be dealt with. PA1 (c) Especially importantly, pumping any fluid to a high pressure creates heat that must be dissipated somehow. This is specially true in gasoline engines where the injectors are designed to and must meter liquid fuel, rather than fuel vapors. PA1 It is understood that various automotive vehicle manufacturers and others are going to the expense of trying to develop means to overcome vapor and other hot fuel handling problems that complicate the metering function. PA1 (d) Additionally, pumping maximum fuel at the required pressure causes unnecessary motor/pump wear. PA1 (1) having means such that although the d.c. pump drive motor speed is constant, the driven pump speed is controlled to a speed proportional to vehicle engine speed; PA1 (2) wherein the positive displacement pump is driven by a d.c. electric motor, but wherein the drive connection between the d.c. motor and the pump comprises means adapted to drive the fuel pump at a speed directly proportional to engine speed; PA1 (3) wherein the drive connection means between the motor and the pump comprises a magnetic clutch, and wherein means is provided for controlling the operation of the clutch in a manner so that the d.c. motor effectively drives the pump at a speed directly proportional to engine speed; PA1 (4) wherein proper fuel metering is dependent upon maintenance of a constant required system fuel pressure, as by a pressure regulator, but wherein the quantity of fuel supplied by the fuel pump is in direct proportion to engine speed; PA1 (5) wherein a d.c. electric motor drives a positive displacement fuel pump, the drive connection between the motor and the pump being designed and controlled so as to be infinitely variable and adaptable to drive the pump at a speed that is continuously directly proportional to the instantaneous value of engine speed, so as to eliminate EXCESSIVE by-passed fuel; PA1 (6) wherein the pump speed is dependent upon the value of at least one other engine operating parameter, or a combination of other engine operating parameters, so as to reduce the quantity of by-passed fuel or even completely eliminate the need to by-pass any fuel; PA1 (7) wherein the pump drive connection includes a variable magnetic clutch, being variably controlled electronically, whereby the drive motor can function independently of the driven pump, such that even though motor speed may at times vary for reasons such as varying applied power voltage caused by varying loads on the electrical system, the fuel pressure in the pump discharge line will remain constant, possibly even in a no by-pass system, such as taught in U.S. Ser. No. 07,662,568, but by means other than d.c. drive motor control, since the magnetic clutch will compensate for variations in power voltage and/or wear in the drive motor and/or pump; PA1 (8) wherein the fuel pump assembly comprises at least two electrical components, one component being the d.c. electric drive motor and the other component being an electrically operated and controlled drive connection between the drive motor and the pump, whereby the motor and the pump can operate or be controlled independently so that, for example, motor speed can be controlled by a single or integrated voltage input, variable in accordance with a single or plurality of sensed parameters, the controlled components cooperating to provide the desired fuel quantity to the fuel injector(s); PA1 (9) wherein the fuel pump is a positive displacement pump driven by the engine (as opposed to the d.c. motor-driven pump) and designed to pump a quantity of fuel directly proportional to engine speed, whereby, in contrast to the above-described present day system, the quantity of pumped and by-passed fuel is greatly reduced, thereby greatly reducing the disadvantages and problems of present day EXCESSIVE by-pass systems; PA1 (10) wherein the pump is driven in any suitable manner (as by gear, clutch, chain, or belt, for example) by any engine part (ignition distributor, cam shaft, or the like) operating in direct proportion to engine speed; PA1 (11) wherein (a) the pump drive motor and (b) the drive motor/pump drive mechanism are separately powered and controlled so as to be capable of independent speed adjustment, and the speed of one is modified by the speed of the other; PA1 (12) wherein a fuel pump is driven at a speed directly proportional to engine speed supplying fuel to the engine (consumed fuel) and a by-pass means returns excess fuel not required by the engine (by-pass fuel) to the fuel tank or sump, the pump being driven at a variable speed directly proportional to variable actual engine speed, rather than at a constant maximum speed required to supply the maximum quantity of consumed fuel the engine could ever require, whereby the quantity of fuel being by-passed is eliminated or substantially less that the EXCESSIVE quantity by-passed in current systems; PA1 (13) wherein the system eliminates by-pass of substantial quantities of fuel required at WOT when actual engine speed is low, such as curb idle speed; PA1 (14) wherein proper fuel metering is dependent upon maintenance of a constant required system fuel pressure, as maintained by a pressure regulator, but wherein the quantity of fuel supplied by the fuel pump is is direct proportion to the engine speed. PA1 (a) means are provided wherein the speed of a fuel pump driven by a variable speed electric motor is controlled in accordance with pressure and/or flow conditions in the fuel by-pass conduit, PA1 (b) use is made of a variable supply of fuel to not only supply the quantity of fuel required to maintain the correct pressure in the injector supply conduit, but to supply that amount of fuel plus some quantity of fuel "Q" to make sure that the by-pass valve (pressure regulator) is always by-passing some, but a minimum, amount of fuel, PA1 (c) the fuel "Q" in above (b) is dependent upon and determined by the effect of transient conditions and the inability of a variable fuel supply systems to maintain the system design fuel pressure in the injector fuel supply conduit, PA1 (d) the fuel "Q" in (b) above is minimal as compared to the EXCESSIVE by-pass in current systems, PA1 (e) the means in (a) above includes a pressure transducer and a down stream restriction for the fuel by-pass conduit, the transducer transmitting pressure signals to an electronic control unit, which, in turn, transmits speed control signals to a variable speed electric motor/fuel pump assembly, PA1 (f) the means in (a) above includes a flow transducer in the by-pass conduit, the transducer transmitting signals to an electronic control unit, which, in turn, transmits speed control signals to the motor/pump assembly referred to in (e), PA1 (g) the means in (a) above includes a differential pressure transducer sensing and transmitting signals representative of the differential between the pressure in the injector feed conduit and the by-pass conduit to the electronic cotrol unit, which, in turn transmits speed control signals based on the differential pressure signals, to the motor/pump assembly, and PA1 (h) the variable speed electric motor/fuel pump assembly referred to above contemplates possible use of a constant speed electric motor driving the pump through a magnetic clutch, as already referred to above.
However, it is a fact that the quantity of fuel consumed by the engine is dependent mainly upon engine speed. As shown later in this specification, fuel consumed by the engine varies with different loads, but a change in engine speed (RPM) results in the most significant change in fuel consumption. In other words, while cold ambient temperatures and other power-demanding equipment increase the fuel consumption, by far, the greatest factor effecting fuel consumption is engine speed.
The fuel pump component of current state-of-the-art gasoline injection systems is typically a constant speed, positive displacement electric pump driven by a d.c. electric motor activated by turning the vehicle ignition switch to the ON position and designed to continuously (so long as the ignition switch is ON) supply the maximum quantity of fuel that will possibly ever be required by the engine under the most severe conditions of speed, load, low ambient temperature, etc., with all other power-demanding systems (air conditioning, heater, radio, lights, windshield wipers, etc.) operating.
However, since much more than 50% (possibly as much as 90%) of normal vehicle operation requires only a very small portion (possibly about 20%) of the above-mentioned continuous, total, maximum-required fuel pump output, it is necessary to by-pass the excess fuel (pumped to 30-40 psi) that is not required by the engine during most normal operating conditions back to the fuel tank or to sump pressure, through a by-pass conduit that normally carries a much greater volume of fuel than the conduit carrying fuel to be consumed in the engine cylinders. Obviously, total pumped fuel equals consumed fuel plus by-passed fuel, and it does not make sense to pump, at low curb idle engine speed and power, as when stopped at a red traffic signal with no accessories operating, the quantity of fuel required at wide-open throttle (WOT) high engine speed operation, with all accessories operating. Such by-pass of most of the pumped fuel (hereinafter referred to as "EXCESSIVE" by-pass) should be either completely eliminated, as proposed in the above-referenced U.S. application Ser. No. 07,662,568, or reduced to a minimum, which is a main object of this invention.
As explained in U.S. application Ser. No. 07,662,568, such EXCESSIVE fuel by-pass creates serious inherent problems, such as the following, for example:
The need to increase automotive fuel efficiency, to reduce noxious automotive exhaust emissions, to improve automotive engine performance, to meet world competition and ecological standards, and to conserve energy, is a continuing need of ever increasing importance that will not go away. In fact, it is understood that the U.S. patent and other laws provide for special considerations, such as expedited handling and mandatory licensing, regarding patent applications/patents covering inventions relating to conservation of energy.
Further, the automotive/gasoline industries are so huge that seemingly minute improvements in a single automobile produces astronomical results, when multiplied by the world vehicle population.
The importance of fuel economy is evidenced by the fact that a prominent automobile manufacturer recently announced it's plan to market a vehicle having a system to shut off the engine when it is not needed, such as when stopped at a traffic light or when coasting downhill, and to restart the engine when needed. Reportedly, the system development indicates feasibility, a main remaining problem being public acceptance of the concept.
Such matters are the very essence of the responsibilities of the U.S. Environmental Protection Agency (EPA) and Department of Energy, as well as various state agencies such as the California Air Resources Board (CARB) to which the EPA looks for leadership in the matter of air pollution control.
Prior to present day electronic gasoline fuel metering, an engine-driven fuel pump was used to supply fuel to the fuel bowl(s) of a carburetor, and the pump supplied only the amount of fuel required (being consumed) by the engine. This pump was unique, in that it was truly a variable displacement pump which pumped fuel only on demand, so that the fuel system did not require a fuel by-pass conduit back to sump pressure or the fuel tank.
However, the above diaphragm pump became impractical and obsolete with the advent of electronic fuel metering systems, since the fuel pressure requirement was increased from about 4-6 psi to about 30-40 psi, and the present day electric fuel pumps described above were substituted, at least in part to enhance electronic fuel system control, resulting in the above problems. It is believed that there have not been, and that there are not now, any engine-driven, gasoline fuel pumps in use, providing the fuel pressures necessary for current fuel injection systems.